MONTPELIER — U.S. Sen. Bernie Sanders said Monday he’ll oppose any effort to raise the age when people become eligible for Medicare health insurance coverage.

Republicans in Congress have proposed raising the age when retirees are eligible for Medicare from 65 to 67. They also want to reduce cost-of-living adjustments for Social Security recipients.

Sanders held a news conference to outline his opposition to those changes, which are being discussed as part of negotiations in Washington to head off a series of tax increases and spending cuts scheduled to take effect next month.

The left-leaning independent took aim at a series of changes to cost-of-living increases that he said would hurt both seniors and disabled veterans, known as “chain CPI.”

If the changes are enacted, “What that would mean for seniors who are 65 today is that by the time they are 75 ... they would get $560 a year less than they would get otherwise,” he said. “By the time they were 85, they would get $1,000 less.”

Sanders acknowledged that raising taxes on the top 2 percent of earners to Clinton-era levels, as President Barack Obama is seeking to do, would erase just about a quarter of the projected deficits in the coming years.

On another topic, Sanders renewed his complaint that gasoline dealers in northwestern Vermont are charging prices at the pump that are higher than both the national average and prices elsewhere in the state, an issue he hopes the Vermont Legislature will address when it begins its new session next month.

Gasoline dealers in Chittenden, Franklin and Grand Isle counties “are keeping gas prices artificially high simply because they can,” Sanders said. “No one is disputing that gasoline distributors have a right to make a profit,” he said. “In my view, however, they should not be ripping people off in these tough economic times.”

Sanders said gas could be bought this past weekend for as little as $3.39 a gallon in Ludlow, in south-central Vermont, while prices in northwestern Vermont were running between $3.65 and $3.70.

Officials with two of the companies Sanders named, SB Collins and Champlain Oil, did not immediately reply to messages seeking comment.

Rodolphe “Skip” Vallee, chairman and CEO of R.L. Vallee Inc., a third company named by Sanders, said in an email, “We are competitive in every market we are in. “ He also complained that Sanders had interfered in the siting review process for discount retailer Costco’s plan to open a cut-rate gas station in Colchester. That project has been under review for five years, Sanders said, calling that “a very long time for a decision.”